This invention relates to a microfluidic switch for stopping a liquid flow during a time interval in a first channel. The liquid flow is to be stopped at the end of the first channel by a stopping means for the defined time interval. After the time interval expires the liquid flow is to be continued. The first channel of the microfluidic switch as well as other channels can be a widening such as for example a cavity and/or a chamber. This channel can be a groove in the surface, which is preferably closed with a cover. Likewise it is possible for the channel to be made as a tube. A channel for the purposes of the invention can fundamentally be any structure, which is suited for routing a liquid or a gas in one certain direction during transport.
A microfluidic switch of the initially mentioned type can be used for example in microfluidic arrangements as known among others from documents WO 99/46045 and U.S. Pat. No. 6,296,126 B1.
For various wet chemical, biochemical and diagnostic analyses it is necessary for the sample liquid to be mixed with reagents for example in a the reaction chamber of a microfluidic arrangement during a defined time interval, during this time interval then the sample liquid being reacted with the reagents into a product. This product is then removed from the reaction chamber in order to be analyzed. The stopping means for known microfluidic arrangements are generally made as mechanical valves, which must be triggered from the outside. These valves are used to fluidically separate individual reaction chambers or also analysis chambers from one another. Via external time control, for example via a computer, the corresponding incubation times, i.e. the time intervals of the residence of the sample or products in the reaction chambers and/or analysis chambers, can be adjusted.
These microfluidic switches with microvalves have the property that they have mechanically moving parts, which for example are accordingly electrically triggered. This leads to high hardware complexity. In addition, integration of these microvalves into the microfluidic switches is complex, especially when the microfluidic switch is made of plastic.
An object of the invention is to propose a microfluidic switch, which makes it possible to stop the liquid flow at the end of the first channel for a predetermined time interval without the need for electrically triggerable microvalves to restart the liquid flow.